This invention relates to vehicles and other equipment having booms, and in particular to devices for securing such booms to prevent movement thereof during transport of such vehicles.
Vehicles such as cherry pickers, cranes, backhoes and the like usually include a one or two piece boom. Before these vehicles are driven or transported, the boom is usually moved to a stowage position to prevent undue stress on the boom. However, the boom still has a tendency to bounce when the vehicle hits a bump or encounters a turn during transport. This causes significant stress on the joints where the boom is connected to the vehicle and on those portions of the boom which strike other parts of the vehicles. Therefore, it is necessary to secure the boom prior to transport of the vehicle.
Securement of the boom is usually accomplished by providing a boom rest or latch which supports the boom when the boom is moved to its stowage position. Several devices are known for automatically latching a boom.
U. S. Pat. Nos. 2,423,583 and 2,699,314 disclose devices for automatically securing a boom mast on a cargo ship. These devices do not automatically align the boom with the latch and thus require additional operator intervention to provide such alignment.
U.S. Pat Nos. 4,184,803, 4,273,502, 4,278,394, 4,636,132 and 4,370,090 disclose a series of backhoe boom latches requiring manual release of the latch. Additionally, these devices do not support the weight of the boom, which is an important factor in achieving boom stability during transport.
U.S. Pat. No. 4,674,638 discloses a system for dampening boom oscillation during transport by supplying hydraulic pressure to the boom's hydraulic cylinders. However, this system does not latch the boom.
U.S. Pat No. 4,978,243 discloses an automatic boom latch system for an articulated boom movable between use and stowage positions. The boom latch includes a latch member movable between latched and unlatched positions. In the latched position, the latch member engages a latch member receiving means connected to the boom. The latch member is operatively connected to the power supply means which moves the boom, so that the boom may be automatically latched when moved to its stowage position, and automatically unlatched when power is applied to move the boom to a use position. However, varying loads on the boom may cause misalignment and binding between the latch member and the latch member receiving means, thereby hindering the release and/or latching of the mechanism. In addition, larger booms require latches of different lengths due to the increased distance between boom members on larger units, which increased distance is necessitated by the increased size of the hydraulic cylinders of larger booms.
It is thus desired to have a latch that automatically aligns the latch member and the latch member receiving means, and that allows adjustment for use of latch members with various size booms and/or hydraulic cylinders.